Wednesday, June 17, 2015

The Flying Pencil

The
Boeing 757 was an impressive aircraft that followed Boeing's endeavor to bring jet
power to small airports with the 727-100. This small aircraft needed three
engines to fly in and out of regional airports that had small runways or rough
geographic hazards around it. This enabled towns & rural regions a fast link to an airline hub or networks to
other domestic areas. While smaller than the four engined 707s, the 727 was
stretched to the 200 variant to allow medium range and capacity flights from
these same airports (while the smaller 737 series could fly routes with less demand).

But more
powerful engines came around by the 1970s and 1980s. The first jumbo jets were
powered by high bypass engines. These engines had larger fans in front to suck
more air. only a portion of this air could go into the heating chambers of the
engine whilst the rest was turbocharged around the same speed. This meant that
the engine produced more power with less thrust than previous engines, making
them more fuel efficient and less noisy. The designers of the Boeing 757 aircraft took advantage of this. They grabbed
two powerful engines (Rolls-Royce RB211, yes THAT Rolls-Royce, and the Pratt & Whitney PW2000). These
engines are pretty noisy by today's standards but have more than 37,000 lbs of
force each (compare to the 727's engine JT8D that started out with 14,000 and
evolved to 20,000 force)!

As a
result, the 757 could carry more (Maximum Take Off Weight [MTOW] of the 757:
255,000 lbs / 115,680 kg while the
727-200 MTOW: 184,800 lbs / 83,800 kg) and travel almost 3,9 00 miles / 7,222 km away. This meant that airports with
small runways and those with noise limits (like John Wayne Airport in Orange
County, California) where aircraft have to climb and descend steeply around the
runway to minimize noise pollution in the area. And it got elongated with the 300

But
decades have passed and the engines consume more fuel than modern competitors,
like the Airbus A321 & the Boeing 737-900ER (despite the fact that it has
more power). As the years add onto the 757 fuselages, many airliners replace
them with other aircraft. But the legacy of the 757 is not over as it follows
the 727 in the freight market. These magnificent airliners, once again, replace
the 727 as cargo haulers for the foreseeable future. So today you could still
fly with many airliners (like American, United, Icelandair, or Delta), but
you'll be seeing more become steady workhorses for freight companies (like UPS,
FedEx Express, TNT Airways, DHL).